Batman:The Animated Series Wiki
TLL 12 - Gotham filled with laughing gas

A cloud of Smilex spreading throughout Gotham

Smilex is the code name for the toxic gas used by Joker. Other names include Joker Toxin, Happy Gas, Giggle Gas, Laughing Gas, Joker Gas, Joker Juice, Laugh-A-loads, Perma-Smile, Smiley Gas, and Smylex.


TLL 09 - When the going gets tough...

Joker wears a gas mask as he loots Gotham even though he does not need it.

Joker makes this gas at his lair Ace Chemicals. Making this gas is almost as deadly as using it which is why everyone except Joker has to wear gas mask.


TLL 02 - Laughing Gas Garbage

A barge loaded with Smilex driven by Captain Clown

The first time Joker used his Happy Gas was The Last Laugh. Joker used a garbage barge that he stole and modified with a sub under it to distribute the gas. Each run Joker docked the barge at Ace Chemicals and his goons sprayed the trash with Smilex before they departed for Gotham. Joker controlled the barge with an android named Captain Clown while he command the barge below in his sub. Joker used this attack to loot Gotham and to rob an armored car and the Bank of Gotham on April Fools Day. Batman found the antidote and sprayed his suit and gas mask with it and administered it to the citizens of Gotham before he confronted Joker and destroyed Captain Clown. Batman then confronts Joker and the clown falls down a stack. Is this the last of Joker? Not by a long shot.

TLF 01 - Smiling Fish

Joker Fish infected with Smilex

The second time Joker used his gas he poisoned a shipment of fish to steal the copyright. Batman stopped him and the fish were destroyed to prevent it infecting Gotham's cat population.

Joker also has this gas in a small bottle attached to his flower. Anyone sprayed with this gets a lethal dose of Smilex.

Several of Joker's gadgets also contain Smilex these being his buzzer, his hand spike, his flowers, and his present bombs which he delivers to unsuspecting victims.


TLF 29 - Joker Venom

A Joker Grin

TLL 17 - Alfred infected

Alfred exposed to Smilex

Smilex if exposed to people can give them a Joker Grin and it can also kill them. Cats can also be exposed to it but it does not give them a Joker Grin it just kills them. Fish can be given Joker Grins and they can be used as a distribution device to deliver the toxin.